Valving systems such as tubular valving systems, for example, typically employ seals that are slidably sealingly engaged via radial compression in an annular space defined between movable nested tubulars. When closed ports in the two tubulars are positioned on opposing longitudinal sides of the seal and when open are positioned on a same longitudinal side of the seal. Actuation of such valves simply requires longitudinally sliding one tubular relative to the other such that the ports of one of the two tubulars pass by the seal. The seals can however, be damaged upon such movement since the radial compression of the seal is at least momentarily removed when the port is aligned with the seal. Once the end of the port reaches the seal the seal must be recompressed. This recompression sometimes results in the seal being cut. Additionally, flow by the seal while the seal is uncompressed can dislodge or extrude the seal from a recess designed to position the seal. This can result in leakage upon closure of the valve. Operators of tubular valves are always interested in new devices that avoid the foregoing drawbacks.